Esters of acetylenic dibasic alcohols and lower aliphatic dicarboxylic acids having at least one hydroxyl or amino substituent



United States Patent US. Cl. 260-482 9 Claims ABSTRACT OF THE DISCLOSUREEsters especially useful as brightening agents in electro plating bathsare prepared by reacting (A) a substituted aliphatic carboxylic acidhaving two to four carbon atoms and at least one substituent selectedfrom the group consisting of hydroxyl and amino groups and (B) anacetylenic dibasic alcohol having not more than eight carbon atoms and astructure in which the hydroxyl groups are attached to the terminalcarbon atoms and the acetylenic bond is not associated with the terminalcarbon atoms.

This application is a division of application Ser. No. 319,982 filedOct. 30, 1963, which matured into US. Patent 3,306,831 issued Feb. 28,1967.

This invention relates, in general, to novel electroplating brightenermaterials, electrolyte compositions and methods of electroplating. Moreparticularly, this inven tion relates to novel ester products which haveutility as additives to nickel, cobalt, nickel-cobalt and copper platingelectrolytes.

Bright nickel, cobalt, and nickel-cobalt alloy coatings may be achievedby buflfing dull electrodeposits to a high luster. However, certainorganic compounds may be added to standard plating baths to producebright deposits initially and eliminate the necessity for bufling. Suchbaths are known as bright plating baths and the additives are known asbrighteners. The formulation of bright plating baths is complex and thecomplexity is compounded by further additions or formulations to makethe deposit ductile and to attain a leveling action in the bath in orderto cover surface imperfections, all in a wide current density range.

Addition agents are also employed in copper plating electrolytes forgrain refinement, brightness, leveling and to improve other propertiesof the copper deposit. Some addition agents contain sulfur and whilethey function effectively as brightening agents the codeposition ofsulfur tends to make the copper deposits brittle. Other ad ditives areeffective grain refining agents at lower temperatures but lose theireffectiveness at elevated temperatures.

Accordingly, it is the general object of this invention to provide a newclass of materials which may be employed as additives in copper, nickel,cobalt and nickelcobalt alloy electroplating baths.

A more specific object of this invention is to provide electrolytes fromwhich bright, ductile and leveled nickel, cobalt and nickel-cobalt alloycoatings may be electrodeposited easily and consistently.

Another object of this invention is to provide methods foreleetrodepositing bright, ductile and leveled coatings of nickel, cobaltand nickel-cobalt alloys.

Yet another object of this invention is to provide electrolytes andmethods for electrodepositing fine grained, lustrous and ductile coppercoatings over a wide plating bath temperature range.

It has now been discovered that a novel class of materials may beprepared by the reaction of (A) a hydroxy or amine substituted aliphaticcarboxylic acid having from two to four carbon atoms with (B) at leastone acetylenic dibasic alcohol having not more than eight carbon atoms.The alcohols have the structural formula:

in which X is selected from the group consisting of:

Examples of suitable acids include glycine and betaalanine and lactic,alpha-hydroxy propionic, beta-hydroxy propionic,alpha-hydroxy-gamma-amino butyric, malic, glycolic, tartaric,beta-hydroxy butyric and aspartic acids.

Acetylenic dibasic alcohols having not more than eight carbon atoms anda structure in which the hydroxyl groups are attached to the terminalcarbon atoms and the acetylenic bond is not associated with the terminalcarbon atoms may be employed. Examples of suitable alcohols includebutynediol, octadiynediol, 3-methy1- pentynediol-2,hexadiyne-2,4-diol-1,6-hexa-3 yne-1,6-diol and pentyne-l,5-diol.

The reaction is conducted in an aromatic hydrocarbon liquid. The chargeof acid and alcohol is refluxed in a vessel equipped with a water trap.After the reaction is completed, i.e., when the theoretical water ofcondensation has been accumulated in the trap, the aromatic hydrocarbonin the reacted charge is removed by vacuum evaporation. The residue isdiluted with water and carbon treated to remove traces of the aromatichydrocarbon and other impurities. This reaction product, without furtherpurification, may be added to electroplating baths as a brighteningagent. It is believed that the reaction product is essentially orprimarily the ester of the described hydroxy and/or amino substitutedacids and the described acetylenic alcohols. It is also believed thatthese esters are eflicacious brighteners as described hereinbelow. Sidereactions apparently take place and, as noted, the reaction productitself may be employed to avoid the cost of purification.

The following examples will specifically illustrate the reaction productbrighteners, electrolytes and plating methods in accordance with thisinvention but should not be considered as limitations on the scope ofthe invention.

EXAMPLE I About 0.1 mole of glycine and 0.1 mole of butynediol areintimately mixed and placed in a 500 ml. flask. The mixture is coveredwith 300 ml. of dry toluene. The flask is fitted with a water trap and areflux condenser. The reaction mixture is refluxed for 40 hours. Duringthis time, about 0.1 mole of water is collected in the water trap. Thetoluene is decanted from the brown residue in the flask. The residualtoluene is then removed by vacuum stripping. The residue in the flask isdispersed in water and filtered to remove the insoluble polymericmaterial. The resultant brown musty smelling liquid is employed as anadditive to electroplating baths or electrolytes as outlined in theexamples hereinbelow.

3 EXAMPLE II About 1 mole of threonine and 1 mole of octadiynediol arereacted in the manner outlined in Example I, hereinabove. The resultingtan solution is employed as an additive in the examples outlinedhereinbelow.

EXAMPLE III About 0.15 mole of alanine is ground together with 0.1 moleof sublimed butynediol. The mixture is placed in a 500 ml. flask andcovered with 300 ml. of dry benzene. The reaction mixture is distilleduntil about 0.1 mole of water is collected in the Water trap. Thebenzene is removed by distillation under reduced pressure. The resultingbrown solid is dispersed in water, carbon treated and filtered. Theproduct is a brown solution and is employed as an additive toelectroplating baths in the examples hereinbelow.

EXAMPLE IV About 1.5 mole of lbeta-aminobutyric acid and 1 mole ofbutynediol are reacted in toluene until 1.3 mole of water is collectedin the water trap. The toluene is decanted and stripped from the solidby vacuum distillation. The residue is dispersed in water. The solutionis filtered and the filtered solution is employed as an additive in theexamples below.

EXAMPLE V About 0.8 mole of beta-aminopropionic acid and 1 mole ofbutynediol are reacted in xylene by refluxing the charge for about 60hours. In this time, about 0.85 mole of water is collected in the trap.The xylene is decanted. The residual xylene is vacuum stripped and theresidue is dispersed in water. The solution is filtered and the filteredsolution is employed as an additive in the examples below.

EXAMPLE VI baths as illustrated by the following specific examples:

' EXAMPLE v11 NiSO .6H O oz./gal 40.0 NiCl .6H O oz./gal.. 6.5 H BOoz./gal 5.0

Reaction product of glycine and butynediol, based on 100% solids oz./gal0.002 Temperature C 150 pH 3.4

A S-ampere Hull Cell panel is plated for 5 minutes from this bath. Thenickel electrodeposit is hazy-bright, leveled and fairly ductile.

EXAMPLE VIII A 3-ampere Hull Cell panel is plated from this .bath. Thepanel is bright and leveled in the current density range of 10 to 140amps/sq. ft. Moreover, the electrodeposit was highly ductile.

EXAMPLE IX NiCl .6H O oz./gal 30.0 H BO oz./gal 5.5 Disodium salt of2,5-benzenedisulfonic acid oz./gal 3.0 Saccharin oz./gal 0.1 Reactionproduct of threonine and octadiynediol, based on solids oz./gal 0.0015Temperature F 150 pH 3.8

The deposit of nickel from this bath will be full-bright in the range of5 to 300 amps/sq. ft. The deposit will be ductile and have a fair degreeof leveling.

EXAMPLE X CoSO 7H O oz./gal 65 NaCl oz./gal 2 H 30 oz./gal 6 Reactionproduct of malic acid and octadiynediol,

based on 100% solids oz./gal 0.03 Temperature F pH 3.8

A leveled and fairly ductile deposit is obtained. The deposit will bebright in the current density range from 10 to 200 amps. sq./ft.

EXAMPLE XI NiSO -6H O oz./gal 32 NiCl 6H O oz./gal 4 CoSO -7H O oz./gal0.4 H BO oz./gal 4 (NH SO oz./gal 0.1 Sodium salt of2,7-naphthalenedisulfonic acid oz./ gaL 2.0 Reaction product of alanineand butynediol, based on 100% solids oz./gal 0.2 Temperature F 140 pH3.8

The nickel-cobalt alloy electrodeposit on a 3-ampere Hull Cell panel isfull-bright and leveled.

EXAMPLE XII NiSO 61-1 0 oz. /gal 40.0 NiCl 6H O oz./gal 6.0 H BO oz./gal5.0 Trisodium-1,3,6-naphthalenetrisulfonic acid oz./gal 3.0 Saccharinoz./gal 0.15 Reaction product of glycine and butynediol, based on 100%solids oz./gal 0.015 Temperature "F pH 3 .55

The deposit from this bath is mirror-bright and highly leveled over acurrent density range of 10 to 350 amps./ sq. ft. Moreover, the depositis ductile.

The concentration of the described class of reaction products shouldrange from about 0.001 to 0.02 ounce per gallon when employed in nickel,cobalt or nickelcobalt alloy plating electrolytes. The foregoingconcentration range should be employed both with and without additionaladditives. Additional additives, known in the art ar d to be describedhereinafter may be employed to further improve other properties of thedeposit. A concentration below about 0.001 ounce per gallon will notproduce a significant improvement in brightness while concentrationsabove about 0.02 ounce per gallon, especially in the absence of otheradditives such as saccharin and the sodium styrene sulfonate to bedescribed herein below, may produce deposits with evidence of stresscracking. The optimum concentration range is from about 0.004 to 0.01ounce per gallon.

It has also been discovered that sodium styrene sulfonate is effectivein brightening the deposits of nickel, cobalt and nickel-cobalt alloysfrom their respective electrolytes. A full-bright leveled but somewhatbrittle electrodeposit is produced in standard baths with no otheradditives. Other additives, as for example saccharin, may be employed incombination with the sodium styrene sulfonate to further improve theproperties of the deposit. Saccharin, for example, will further improvethe leveling power of the bath.

The combination of sodium styrene sulfonate and the heretofore describedreaction product additives produce especially desirable and surprisinglyattractive electrodeposits of nickel, cobalt and nickel-cobalt alloys. Amirror-bright, ductile, leveled deposit with a surprising depth of colorwill be produced by electrolytes employing this combination ofadditives. The concentration of sodium styrene sulfonate, both with andwithout additional additives should range from about 0.005 to 1.0 ounceper gallon, the optimum range being from about 0.01 to 0.75 Ounce pergallon.

For example, nickel may be plated in accordance with the followingspecific illustrations.

EXAMPLE XIII NiSO 6H O oz./gal 40.0 NiCl 6H O oz./gal 6.5 H BO oz./gal5.0 Saccharin oz./gal 0.134 Sodium styrene sulfonate oz./gal 0.5Temperature F 150 pH 3.8

A 3-ampere Hull Cell panel is plated in this bath for five minutes. Afull-bright, leveled but somewhat brittle electrodeposit is produced.

EXAMPLE XIV NiSO -6H O oz./gal 40.0 NiCl 6H O oz./gal 6.5 H BO oz./gal5.0 Saccharin oz./gal 0.134 Reaction product of glycine and butynediol,based on 100% solids of./gal 0.004 Sodium styrene sulfonate oz./gal 0.01Temperature F 150 pH 3.8

A 3-ampere Hull Cell panel is plated in this bath for five minutes. Thepanel is mirror-bright, highly leveled and ductile. The bath hasexcellent throwing power.

I have also discovered that the reaction product of glycine andbutynediol is an effective grain refining agent in copper electrolytes.In copper plating baths, the concentration of the glycine-butynediolreaction product should range from about 0.002 to 0.07 ounce per gallonand preferably from about 0.004 to 0.05 ounce per gallon. This additiveis an effective grain refining agent at elevated temperatures, e.g. at140 E, where some other additives lose their efiicacy.

For example, copper may be plated in accordance with the followingspecific illustration.

EXAMPLE XV A 3-ampere Hull Cell panel is plated from the above bath. Thepanel is ductile, finely grained and semi-bright. The bath has excellentthrowing power.

While there have been shown and described what are presently consideredto be the preferred embodiments of the invention, modifications theretowill readily occur to those skilled in the art. It is not desired,therefore, that the invention be limited to the specific arrangementsshown and described and it is intended to cover in the appended claimsall such modifications as fall within the true spirit and scope of theinvention.

I claim as my invention:

1. An ester of (A) an alkanoic acid having from 2 to 4 carbon atoms andat least one substituent selected from the group consisting of hydroxyland amino groups and (B) an acetylenic dibasic alcohol having not morethan 8 carbon atoms and a structure in which the hydroxyl groups areattached to the terminal carbon atoms and the acetylenic bond is notassociated with the terminal carbon atoms.

2. An ester as claimed in claim 1 which is water soluble and in which(A) is an alkanoic acid having from 2 to 4 carbon atoms and at least onesubstituent selected from the group consisting of hydroxyl and aminogroups and (B) is an acetylenic dibasic alcohol containing not more than8 carbon atoms and having the formula:

HOCH X-CH OH in which X is selected from the group consisting of 3. Anester as claimed in claim 1 in which (A) glycine and (B) is butynediol.

4. An ester as claimed in claim 1 in which (A) potassium acid tartrateand (B) is butynediol.

5. An ester as claimed in claim 1 in which (A) threonine and (B) isoctadiynediol.

6. An ester as claimed in claim 1 in which (A) alanine and (B) isbutynediol.

7. An ester as claimed in claim 1 in which (A) malic acid and (B) isoctadiynediol.

'8. An ester as claimed in claim 1 in which (A) beta-aminobutyric acidand (B) is butynediol.

9. An ester as claimed in claim 1 in which (A) i beta-aminopropionicacid and (B) is butynediol.

References Cited UNITED STATES PATENTS 2,164,188 6/1939 Groll et al260--484 XR 2,520,750 8/ 1950 Wilkinson 260488 2,809,988 10/1957Heininger 260 484 XR 2,901,516 8/1959 Wynn 260-488 XR 3,041,256 6/1962Kleiner et al. 20449 XR 3,107,222 10/1963 Riggs 252389 3,226,426 12/1965Hopkins et al. 260482 3,306,831 2/1967 Cope 204-43 OTHER REFERENCESKampschulte et al., Chem. Ab. vol. 53: 21,292f (1959). Hanson-VanWinkle-Munning Co., Chem. Ab. vol. 55: 24,331('b) (1961).

LORRAINE A. WEINBERGER, Primary Examiner ALBERT P. HALLUIN, AssistantExaminer US. Cl. X.R. 260484

